added release notes for alerting (#1619)

* added release notes for alerting

Signed-off-by: Riya Saxena <riysaxen@amazon.com>

* added release notes for alerting

Signed-off-by: Riya Saxena <riysaxen@amazon.com>

---------

Signed-off-by: Riya Saxena <riysaxen@amazon.com>
(cherry picked from commit e22cd76)
Signed-off-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

release-notes/opensearch-alerting.release-notes-2.16.0.0.md

@@ -0,0 +1,18 @@
+## Version 2.16.0.0 2024-07-25
+Compatible with OpenSearch 2.16.0
+
+### Maintenance
+* Increment version to 2.16.0-SNAPSHOT. ([#1589](https://github.com/opensearch-project/alerting/pull/1589))
+
+### Bug Fixes
+* Fixing build script to only publish alerting zip ([#1605](https://github.com/opensearch-project/alerting/pull/1605))
+* fix pluginzippublish issue ([#1604](https://github.com/opensearch-project/alerting/pull/1604))
+
+### Enhancements
+* Enable cross-cluster monitor cluster setting ([#1612](https://github.com/opensearch-project/alerting/pull/1612))
+* Register system index descriptors through SystemIndexPlugin.getSystemIndexDescriptors ([#1594](https://github.com/opensearch-project/alerting/pull/1594))
+* commits to support remote monitors in alerting ([#1589](https://github.com/opensearch-project/alerting/pull/1589))
+
+
+### Documentation
+* Added 2.16 release notes. ([#1619](https://github.com/opensearch-project/alerting/pull/1619))